Process for producing prostaglandin acids

ABSTRACT

An esterase enzyme composition comprising the acetone-insoluble matter left on extracting lipids from the marine invertebrate Plexaura homomalla (Esper), 1792, useful for transforming esters of prostaglandins and prostaglandin-like materials to their acid forms.

United States Patent- [191 Daniels Oct. 8, 1974 PROCESS FOR PRODUCING PROSTAGLANDIN ACIDS [75] Inventor: Edward G. Daniels, Portage, Mich.

[73] Assignee: The Upjohn Company, Kalamazoo,

Mich.

[22] Filed: Apr. 26, 1973 [21] Appl. No.1 354,332

Related U.S. Application Data [62] Division of Ser. No. 216,8]5, Jan. l0, 1972, Pat. No.

[52] US. Cl. 195/30 [51] Int. Cl C12d 1/02 [58] Field of Search 195/30 [56] References Cited UNITED STATES PATENTS 3,769,166 10/1973 Leeming ..195/30 Primary Examiner-Alvin E. Taneholtz Attorney, Agent, 0r FirmMorris L. Nielsen ABSTRACT An esterase enzyme composition comprising the ace- 4 Claims, N0 Drawings 1 PROCESS FOR PRODUCING PROSTAGLANDIN ACIDS BACKGROUND OF THE INVENTION This is a division of application Ser. No. 216,815 filed Jan. 10, 1972, now US. Pat. No. 3,761,356.

This invention relates to an enzymatic process for transforming prostaglandin esters to their acid forms, to a novel esterase enzyme composition used in that process, and to a process for producing said composition.

The prostaglandins are derivatives of prostanoic acid which has the following structure and atom numbering:

Prostaglandins are known in the art; See, for example,

the terms PGE PGA,, and the like, will mean the optically active form of that prostaglandin or prostaglandin-like material with the same absolute configuration as PGE, obtained from mammalian tissues. Included within the scope of this invention are also the corresponding racemic forms, consisting of the optically active compounds of natural configuration and their enantiomorphs. When reference to the racemic ample dl-PGE Following the usual conventions,

Bergstrom et al. Pharmacol. Rev. 20,1 (1968), and references cited therein. For example, prostaglandin E (PGE has the following structure:

COOH

Other prosfi glandirKiind prostaglandinlike com- 3 5 pounds within the scope of this invention are prostaglandin A (PGA prostaglandin E (PGE prostaglandin A (PGA 13,14-dihydro-PGE 13,14- dihydro-PGA l5-methyl (or ethyl)-PGE,, -PGA PGE PGAz, ,PGE and PGA 13,14-dihydro-15-methyl (or ethyl)-PGE,, l3,l4-dihydro-l5- methyl (or ethyl)-PGA their ISB-epimers, and their 'racemates. These compounds and their methyl or ethyl esters are known in the art or are available by methods known in the art. See, for example, Bergstrom et al., cited above, Pike et al., J. Org. Chem. 34, 3552 (1969); Schneider et al., J. Am. Chem. Soc. 91, 5372v (1969); Axen et al., Chem. Comm. 1970, 602; Bundy et al., Annals NY. Acad. Sci. 180, 76-90 (1971); US. Pat. Nos. 3,069,322 and 3,598,858; British Pat. Nos. 1,040,544, 1,097,533, and 1,202,010; and West Germany Offenlegungsschrift No. P 21 21 980.7.

The prostaglandins are extremely potent in causing various biological responses and accordingly are useful for pharmacological purposes. See, for example, Bergstrom et al., and other references cited above. Other prostaglandin-like compounds produced in their acid form by this invention are each useful for at least one of the pharmacological purposes indicated for the prostaglandins, and are used for those purposes in the same manner as the prostaglandins.

The prostaglandins are obtained in a particular optically active form from certain mammalian tissues, for example, sheep vesicular glands, swine lung, and human seminal plasma, or by reduction or dehydration of a prostaglandin so obtained. See, for example, Bergstromet al., cited above, and Nugteren et al., Nature 212, 38 (1966). For convenience hereinafter, use of the hydroxy at 015 is shown in alpha configuratiomas in H6. 11, by broken line attachment. Compounds with epi (R) configuration for the hydroxy at C1 5 are so designated by using IS-beta in the nameqThus, the ISB-epimer. of PGE: is named 15B-PGE,. The corresponding 15B-epimers are likewise within the scope of this invention.

of transforming prostaglandin esters to their acid forms. It is afurther purpose to provide a novel esterase enzyme composition useful for that purpose. It is still a further purpose to provide a process for preparing said composition.

Utilization of the prostaglandins and prostaglandinlike materials often requires that they be available in free acid form. They can then be transformed into other desired forms for effective administration,- for example salts or esters. However, the prostaglandins and prostaglandin-like materials are not always available in their acid form: when synthesized, they sometimes are obtained as methyl or ethyl esters; in some instances the products are stored as methyl or ethyl esters for stability reasons; and in still other instances these esters may be produced because they provide a preferred form for purification, as by silica gel chromatography. The present invention provides a means of transforming such esters to their acid form in high yield without degradation as an improvement over conventional chemical methods.

I have found an esterase enzyme composition suitable for this purpose. This composition is obtained by processing the marine invertebrate, Plexaura h'0m0 malla. Plexaura homomalla is a member of the subclass Octocorallia, order Gorgonacea, suborder Holaxonia, family Plexauridae, genus Plexaura. See, for example, Bayer, The Shallow-Water Octocorallia of the West Indian Region, Martinus Nijhoff, The Hague (1961 Colonies of these Plexaura homomalla are abundant on the ocean reefs in the zone from the low-tide line to about 25 fathoms in the tropical and subtropical regions of the western part of the Atlantic Ocean, from Bermuda to thereefs of Brazil, including the eastern shore reefs of Florida, the Caribbean island and mainland reefs, and the Gulf of Mexico island and mainland reefs. These colonies are bush-like or small tree-like in habit and are readily identified for collection as Plexaura homomalla (Esper), 1792, by those of ordinary heimer et al., Tetrahedron Letters, No. 59, 5185 (1969), and H. W. Youngken, Jr. (ed.), Food-Drugs from the Sea, Proc. Marine Technology Society, pp. 311-314 (1969). The 8" Form is a source of S- I configuration prostaglandins, such as PGA One method of distinguishing the two' forms is described below in Preparation 1. For the purposes of this invention eitherform R or forms is useful.

' The esterase enzyme composition is produced by the steps: (1) extracting colonies or colony pieces of the marine invertebrate Plexaura homomalla (Esper),

' 1792, forma R or forma S, with liquid acetone for a sufficient time to remove substantially all soluble lipids,

I in their as-harvested form or in broken or chopped pieces. It is immaterial whether they are used fresh from their .natural environment, or after freezing and thawing, or even after drying under ambient condi- V tion's. I g

The extraction with acetone may be done batch-wise, as by stirring in-a container, or by percolation, or by continuous methodsof extraction known in the art. If 0 stirring is used, it is advantageous to first chop the Plexaura homomalla into small pieces, for example less than 3 mm. in greatest dimension. The 'product.is accordingly then a powder consisting of pieces smaller than 3 mm. Contact with acetone is continued until substantially all of the soluble lipids are removed. Normally l vhour is sufficient, although a longer time is required for whole colonies and a shorter time is sufficient for chopped colonies with efficient extraction. The endpoint can be determined simply by examination of the acetone, as by evaporation and by physical measurements on any residue thus obtained. The extraction temperature is kept below 50 C. to avoid denaturation of the enzyme, and is preferably in the range to C. Lower temperatures may be used but the extraction then proceeds more slowly. The extraction is generally done at atmospheric pressure, but it may be carried out at higher or lower pressures provided the acetone is in a liquid state when contacting the Plexaurahomomalla.

Other lipophilic liquids may be used, although generally less effectively than acetone: for example, methanol, methanol-chloroform, 'dichlorornethane, or

ethanol-ether.

The acetone-insoluble enzyme composition is recovered from, the acetone by decantation, filtration, cenfrom the above composition by so'lubilizing it with an aqueous detergent solution, separating the solution from the skeleton and spicule matter of the invertebrate, and reprecipitating the enzyme esterase as a powder with acetone.

An advantage of the enzyme composition of this invention is that the enzyme is immobilized. The composition is readily recovered from the hydrolysis mixture, for example by filtration, and, after suitable washing and drying, is available for reuse numerous times.

ln utilizing the above esterase enzyme composition for the purposes of this invention, the prostaglandin ester is contacted with a mixture of the enzyme composition and water. The esteris conveniently added as a solution, for example in ethanol or benzene, to about 504- times its weight of water. The enzyme composition is added in an amount about 1-15 times the weight of ester. The mixture is stirred until the ester is hydrolyzed, generally'about 18-24 hours at 25 C. Temperatures of about O-50 C. may beemployed, although about 25 C. is preferred. The progress of hydrolysis is readily followed by analysis, for example by thin-layer chromatography by methods known in the art. See, for example, l-lamberg et al., J. Biol. Chem. 241, 257 (1966). Finally, several volumes of acetone are added and the soluble acid products are recovered by filtration, concentration, and extraction using methods known in the art.

Accordingly,.there is provided a process for producing an optically active acid of the formula III or a racemic acid of that formula and the mirror image thereof, wherein is either whereinR, is hydrogen, methyl, or ethyl; wherein, ta) X is trans-CH4" or ("IM'H ,aml Ymullarc' both CH CH (b) X is trans-CH=CH, Y is cis-' contacting an optically active compound of the formula or a racemic compound of that formula and the mirror image thereof, wherein R is methyl or ethyl, and

wherein x G, R X, Y, and Z are as defined above, with water and an esterase enzyme composition produced as described herein, and (2) separating said acid.

Formula III, which is written in generic form for convenience, represents PGE-type compounds when Ho and PGA-type compounds when 7' i DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention can be more fully understood by the following preparation and examples.

All temperatures are in degrees Centigrade. Preparation 1 To distinguish Plexaura homomalla (Esper), 1792, forma R from Plexaura homomalla (Esper), 1792, forma S, a TLC method is used. A specimen approximately 2 cm. in length is harvested and placed in a small vial, with a small amount of water if necessary to insure it is wet, and kept closed for 6-24 hrs. About 1 ml. of methanol is then added and the sample is either shaken for 2 hrs. at about 25 C. or is stored for 16-24 hrs. at about 10 C. A sample of the liquid (10-20 ,u.l) is spotted on a TLC plate. It is preferred to use a fluorescent-treated silica gel plate, e.g.,

' Uniplate Silica Gel GF (Analtech, lnc., Newark, Del.

As reference standards, spots of PGA and B-PGA are also applied. The plate is developed in the A-IX system. The A-IX solvent system used in thin layer chromatography (TLC) is made up from ethyl acetateacetic acid-2,2,4-trimethylpentane-water (90:20:502100) according to M. Hamberg and B. Samuelsson, J. Biol. Chem 241, 257 (1966). The spots are finallyvisualized with vanillin phosphoric acid spray (McAleer, Arch. Biochem. Biophys. 66, 120 (1957)). Comparison of the unknown with the two reference spots is then made and the identity of the coral established (forma S corresponding to PGA forma R to 15B-PGA Example 1 Enzyme Composition Freshly harvested colony pieces of Plexaura homomalla (Esper), 1792, forma S (10 kg.), are chopped into pieces less than 3 mm. in their longest dimension, and then covered with about three volumes l.) of acetone. The mixture is stirred at about C for about 1 hour. The solids are separated by filtration. washed with l2 liters of acetone, air dried, and finally stored at about 20 C as a coarse enzymatic-powder. Example 2 Enzyme Composition Following the procedure of Example 1, but replacing Plexaura homomalla (Esper), 1792, forma S with Plexaura homomalla (Esper), 1792, forma R, there is obtained an enzymatic composition.

Example 3 Enzyme Composition Colonies of Pleiaura homomalla (Esper), 1792, forma S (10 kg.) are chopped into pieces, each weighing less than about 2 grams. The chopped material, wet with water, is stored in closed containers for about 24 hrs. at 25 C. and then stirred with about three volumes l.) of acetone at about 25 C. for 1 hour. The solids are separated by filtration, washed with l-2 liters of acetone, and air dried, to yield an enzymatic composition.

combined with a solution of PGE,, methyl ester (US.

Pat. No. 3,069,322, 0.5 g.) in about 0.8 ml. of ethanol. The mixture is stirred at about 25 C. for 24 hrs. Then, ml. of acetone is added, the mixture is stirred briefly and filtered, and the filtrate is concentrated under reduced pressure. The aqueous residue is acidified to pH 3.5 with citric acid and extracted with dichloromethane. The combined extracts are concentrated under reduced pressure to-the title compound; m.pt. 1 l51 17 PGE ethyl ester PGA methyl ester PGE methyl ester PGA methyl ester 13.l4-DihydroPGE ethyl ester there is obtained the corresponding prostaglandin-type acid, namely Following the procedure of Example 5, but replacing PGE methyl ester with dl-PGEg, methyl ester and with the racemic form of each of the above-listed esters, there is obtained the corresponding racemic acid.

Likewise following the procedure of Example 5, but replacing the esterase composition of Example 1 with each of those of Examples 2-4, inclusive, there is obtained PGE, in each case.

I claim:

1. A process for producing an optically active acid of the formula or a racemic acid of that formula and the mirror image thereof, wherein is either wherein R is hydrogen, methyl, or ethylywherein (a) X is trans-CH=CH or CH CH and Y and Z are gen, or (c) X is trans-CH=CH,

Y is cis-CH=CH,

and Z is cis-CH=CH; which comprises the steps:

1. contacting an optically active compound of the formula or a racemic compound of that formula and the mirror image thereof, wherein R is methyl or ethyl, and

wherein v G, R X, Y, and Z are as defined a bove, with water and an esterase enzyme composition produced by the steps:

a. extracting colonies or colony pieces of the marine invertebrate Plexaura 1792, forma R or forma S, w

homomalla (Esper), ith liquid acetone for a sufficient time to remove substantially all soluble lipids, and

b. recovering the acetone-insoluble matter as said composition, and 2. separating said acid. 2. A process according to claim OI CH2CH2', and

1 wherein X is trans- Y and Z are both 3. A process according to claim 1 wherein X is trans- CH=CH-, Y is cis-CH=CH, Z is CH CH and R is methyl or ethyl.

4. A process according to claim CH=CH-, and Y and Z are both 1 wherein X is trans- CH CH 

1. A PROCESS FOR PRODUCING AN OPTICALLY ACTIVE ACIDS OF THE FORMULA
 1. CONTACTING AN OPTICALLY ACTIVE COMPOUND OF THE FORMULA R2-OOC-(CH2)3-Y-CH2-D-X-C(=G)-CH2-Z-CH2-CH3 OR A RACEMIC COMPOUND OF THAT FORMULA AND THE MIRROR IMAGE THEREOF, WHEREIN R2 IS METHYL OR ETHYL, AND WHEREIN D, G,R1, X, Y, AND Z ARE AS DEFINED ABOVE, WITH WATER AND AN ESTERASE ENZYME COMPOSITION PRODUCED BY THE STEPS: A. EXTRACTING COLONIES OR COLONY PIECES OF THE MARINE INVERTEBRATE PLEXAURA HOMOMALLA (ESPER), 1792, FORMA R OR FORMA S, WITH LIQUID ACETONE FOR A SUFFICIENT TIME TO REMOVE SUBSTANTIALLY ALL SOLUBLE LIPIDS, AND B. RECOVERING THE ACETONE-INSOUBLE MATTER AS SAID COMPOSITION, AND
 2. A process according to claim 1 wherein X is trans-CH CH- or -CH2CH2-, and Y and Z are both -CH2CH2-, or X is trans-CH CH-, Y is cis-CH CH-, and Z is cis-CH CH-.
 2. separating said acid.
 2. SEPARATING SAID ACID.
 3. A process according to claim 1 wherein X is trans-CH CH-, Y is cis-CH CH-, Z is -CH2CH2, and R1 is methyl or ethyl.
 4. A process according to claim 1 wherein X is trans-CH CH-, and Y and Z are both -CH2CH2-. 